Fluid cylinders



Dec. 3, 1957 R. SQMAN ET AL 2,315,254

FLUID CYLINDERS Filed March 2a, 1956 2 Sheets-Sheet 1 INVENTORS ROBERTSOMA/Y WILLIAM E. PARKERI CHAUNCEY LOUCKS ATTORNEY I Dec. 3, 1957 FLUIDCYLINDERS R. SOMAN ET AL 2,815,254

Filed March 26, 1956 2 Sheets-Sheet 2 il s \\1 I 2:

IN V EN TORS ROBERT SOMAN W/LL/AM EAR/(ER CHAU/VCEY LOUC/(S BY Z/Wwmu ATTOR/VKY htates Patent @fiice 2,815,254 Fatented Dec. 3, 1957 Loncks,Warren, ()hio, assigmors to The Federal Machine & Welder CompanyApplication March 26, 1956, Serial No. 574,057

6' Claims. (Cl. 309-6) The present invention relates to fluid cylinders,more particularly to fluid cylinders of the type having means forlubricating the relatively movable parts thereof, and the principalobject of the invention is to provide new and improved fluid cylindersof such character.

The problem of lubricating fluid cylinders, particularly certain typesof air cylinders and the like, has never been satisfactorily solved.Attempts have been made to lubricate such cylinders; however, even thebest of the prior constructions were high in initial cost and weretroublesome to maintain since most required a multiplicity of workingparts.

The present invention is characterized by simplicity, low initial costand longv trouble-free operation. These and other advantages willreadily become apparent from a study of the following description andfrom the drawings appended hereto.

In the drawings accompanying this specification and forming a part ofthis application, there is shown, for purpose of illustration, anembodiment which the invention may assume, and in these drawings:

Figure l is an elevational View illustrating an appli cation for whichthe present invention is particularly well suited,

Figure 2 is an enlarged longitudinal sectional view of the invention,

Figure 3' is an enlarged, fragmentary view of a portion of the deviceshown in Figure 2, and

Figure 4 i a view similar to Figure 3 but showing certain parts inanother position.

The fluid cylinder herein illustrated is adapted to be employed as acushioning device for a press; however, it is to be understood that thepresent invention has application in fluid cylinders adapted for otheruses.

The press It) illustrated in Figure 1 may be of any conventional designand is herein shown to comprise a movable platen ill and a fixed support12. The usual power mechanism (not shown) may be employed to reciprocateplaten 11 toward and away from support 12. Press It further incorporatesa cushioning device 13 which illustrates an embodiment of the presentinvention.

Briefly, cushioning device 13 comprises a pair of relatively shiftablemembers interposed between platen 11 and support 12 of the press and inthe present embodiment, the non-movable portion of the cushioning deviceis secured to the support 12. Normally, the movable portion ofcushioning device 13 is resiliently biased to an elevated position;however, when platen 11 descends and exerts a predetermined forcethereon, this portion will be forced downwardly by the moving platen toprevent the latter from exerting more than the predetermined force.

When the platen 11 reaches the end of its stroke and begins to returntoward its upper position, the movable portion of the cushioning devicewill move upwardly with the platen, keeping the force constant, untilthe cushioning device reaches its elevated position and stops. Theplaten 11 will then continue its upward movement alone until it reachesits upper stroke limit. Although not shown, the usual dies or othermaterial working devices will normally be positioned between the platen11 and the cushioning device 13.

As best seen in Figure 2, cushioning device 13 comprises a post-likemember 14 whose lower end is secured to support 12 of the press bysuitable bolts 15 or the like. For a purpose to become evident, theupper end of post 1 is formed to provide a piston 16. Post 14 isprovided with a cavity 17 which provides a sump for containing aquantity of oil or other lubricant. A cylinder member 18 is carried bypost 14 and has a bore 19' in which piston 16 is slidable. The upper endof bore 19 is closed by a wall 20' to provide a chamber 21 forcontaining a compressible fluid such as air. In the present embodimentand for reasons to be disclosed, chamber 21 is in communication with astandpipe 22 which projects above the level of the lubricant in thesump, and which leads to an external surge tank 23.

Means are provided for sealing the operating clearance between piston 16and bore 19, which clearance has been exaggerated in the drawings. Suchmeans presently comprises a plurality of axially spaced annular sealingmem ber which may take the form of conventional U-shaped packing rings.In the present embodiment, the upper end of piston 16 carries sealingmembers 24, 25 secured to the piston by a suitable retaining ring 26.Spaced from sealing member 25 is a sealing member 27 which is carried bythe cylinder member 18 and held in place by a retaining ring 28 which issecured to the cylinder memher by any suitable means, and which forms anextension thereof. In the position of parts shown, the lower end ofretaining ring 28 is provided with an inwardly directed shoulder 29which engages with a shoulder 30 on the post 14 to limit upward movementof the cylinder member relative to the post.

A conduit 3ll is in communication with the space between sealing members25, 27 and conduit 31 is connected to a conduit 32 whose lower end isimmersed in the lubricant in the sump and to a conduit 33 whichterminates adjacent sealing member 24. Suitable check valves 34- and 35are interposed in respective conduits 32, 33 to limit passage oflubricant to the directions indicated by the respective arrows.

For the purpose of indicating the level of lubricant within cavity 17, aconventional sight glass 36 is positioned to one side of the cushioningdevice. The lower end of the sight glass communicates with the bottom ofcavity 17 by means of a conduit 37 while the upper end of the sightglass communicates with the space above the level of the lubricant bymeans of a conduit 38. A suitable fitting 39 is provided in conduit 38to permit introduction of additional lubricant.

Operation of the cushioning device will be as follows: Normally, surgetank 23 will be charged with air under a given pressure, such pressurebeing determined by the desired amount of force to be exerted by thecylinder member 18. Chamber 21 will also be filled with air under thesame pressure which exists in the surge tank since the chamber and thetank are in communication with each other through standpipe 22. Withchamber 21 filled with air under pressure, cylinder member 18 will beurged to its uppermost position shown in Figure 2 and 3.

Downward movement of platen ll of press 10 will ultimately exert adownward force on cylinder member 18 of the cushioning device. However,downward movement of the cylinder member will not occur until the forceexerted by the platen is suflicient to overcome the opposing forceexerted by the air under pressure in chamber 21.

When the force exerted by platen 11 is great enough,

cylinder member 18 will be forced downwardly (see Figure 4). Downwardmovement of the cylinder member will move sealing member 27 away fromsealing member 25 and increase the space between such members. With anincrease in space (or volume) between these sealing members, theresultant reduction in pressure will draw lubricant from the sumpthrough conduits and and into the space between the sealing members x3,to 112- bricate the latter. Note that check valve will prevent fiow offluid in a direction from conduit to conduit When platen 11 movesupwardly, the air in chamber 21 will cause cylinder member 13 to returnto the position shown in Figures 2 and 3. This movement of the cylindermember will move sealing member 27 toward sealing member 25 and decreasethe space between such members. With the decrease in space between thesealing members, lubricant will be forced from the space throughconduits fill and 33 to be discharged by the latter on sealing member24- to effect lubrication thereof. Note that check valve 34 will preventflow of lubricant in a direction from conduit 31 to conduit 32.

From the foregoing it will be apparent that each time cylinder member 18moves downwardly, a charge of lubricant will be drawn into the spacebetween sealing members 25', 2'7 and each time the cylinder member movesupwardly, lubricant will be forced out of the space for discharge on toscaling member 24. Obviously, excess lubricant discharged by conduit 33will flow down the wall of cavity 17 and collect in the bottom to berecirculated.

in view of the foregoing it will be apparent to those skilled in the artthat we have accomplished at least the principal object of our inventionand it will also be apparent to those skilled in the art that theembodiment herein described may be variously changed and modified,without departing from the spirit of the invention, and that theinvention is capable of uses and has advantages not herein specificallydescribed, hence it will be appreciated that the herein disclosedembodiment is illustrative only, and that our invention is not limitedthereto.

We claim:

1. A fluid cylinder comprising a cylinder member having a bore in whicha piston is slidably disposed and said cylinder member and said pistonbeing arranged for relative reciprocating movement, spaced-apart meansfor effecting an annular seal between said piston and said bore andcomprising first annular sealing means carried by said piston andslidably engaged with said bore and second annular sealin means carriedby said cylinder member and slidably engaged with said piston, saidfirst and second means being movable toward and away from each other tocontract and expand the space therebetwcen during relative reciprocationof said cylinder member and said piston, and means for utilizin theexpansion of the space between said first and second means to drawlubricant into such space to lubricate said annular sealing means.

2. A. fluid cylinder comprising a cylinder member having a bore in whicha piston is slidably disposed and said cylinder member and said pistonbeing arranged for relative reciprocating movement, spaced-apart meansfor effecting an annular seal between said piston and said bore andcomprising first annular sealing means carried by said piston andslidably engaged with said bore and sec ond annular sealing meanscarried by said cylinder member and slidably engaged with said piston,said first and second means being movable toward and away from eachother to contract and expand the space therebetween during relativereciprocation of said cylinder member and said piston, and means forutilizing the expansion of the space between said first and second meansto draw lubricant into such space to lubricate said annular sealingmeans and for utilizing the contraction of such space to displacelubricant therefrom.

'5. A fluid cylinder comprising a cylinder member having a bore in whicha piston is slidably disposed and said cylinder member and said pistonbeing arranged for relative reciprocating movement, spaced-apart meansfor effecting an annular seal between said piston and said bore andcomprising first annular sealing means carried by said piston andslidably engaged with said bore and second annular sealing means carriedby said cylinder member and slidably engaged with said piston, saidfirst and second means being movable toward and away from each other tocontract and expand the space therebetween during relative reciprocationof said cylinder member, and said piston, and means for utilizing theexpansion of the space between said first and second means to drawlubricant from a source into such space to lubricate said annularsealing means and for utilizing the contraction of such space todisplace lubricant therefrom for return to such source.

4. A fiuid cylinder comprising a cylinder member having a bore in whicha piston is slidably disposed and said cylinder member and said pistonbeing arranged for relative reciprocating movement, spaced-apart meansfor effecting any annular seal between said piston and said bore andcomprising first annular sealing means carried by said piston andslidably engaged with said bore and second annular sealing means carriedby said cylinder member and slidably engaged with said piston, saidfirst and second means being movable toward and away from each other tocontract and expand the space therebetween during relative reciprocationof said cylinder and said piston, third annular sealing means foreffecting a seal between said piston and said bore at a place spacedfrom said first and second means, and means for utilizing the expansionof the space between said first and second means to draw lubricant intosuch space to lubricate said first and second annular sealing means andfor utilizing the contraction of such space to displace lubricanttherefrom and to said third annular sealing means for lubricating thelatter.

5. A fluid cylinder comprising a cylinder member having a bore in whicha piston is slidably disposed and said cylinder member and said pistonbeing arranged for relative reciprocating movement, spaced-apart meansfor efiecting an annular seal between said piston and said bore andcomprising first annular sealing means carried by said piston andslidably engaged with said bore and second annular sealing means carriedby said cylinder member and slidably engaged with said piston, saidfirst and second means being movable toward and away from each other tocontract and expand the space therebetween during relative reciprocationof said cylinder member and said piston, third annular sealing means foreffecting a seal between said piston and said bore at a place spacedfrom said first and second means, conduit means extending from a sourceof lubricant to the space between said first and second means andextending from such space to adjacent said third means, and valve meansfor preventing flow of lubricant through said conduit means in adirection from adjacent said third means toward the space between saidfirst and second means and for preventing fiow of lubricant through saidconduit means in a direction from such space toward the lubricantsource, expansion of the space between said first and second meansdrawing lubricant into such space through said conduit means tolubricate said first and second means and contraction of such spacedisplacing lubricant therefrom and through said conduit means to saidthird means for lubricating the latter.

6. A fluid cushioning device for presses and the like comprising acylinder member having a generally vertically extending bore, agenerally vertical post Whose upper end provides a piston slidablyfitting with said bore and about which said cylinder member isreciprocable in a generally vertical direction, said piston having arecess extending downwardly from its upper end to provide a sump forstoring a quantity of lubricating fiuid, a plurality of verticallyspaced annular sealing members each adapted to effect an annular sealbetween said piston and said bore and comprising an upper sealing membercarried by said piston and slidably engaged with said bore, a lowersealing member carried by said cylinder and slidably engaged with saidpiston, and an intermediate sealing member disposed between said upperand lower sealing members and carried by said piston and slidablyengaged with said bore, said lower sealing member being movable withsaid cylinder member toward and away from said intermediate sealingmember during reciprocation of said cylinder member to contract andexpand the space therebetween, conduit means extending from the sumpprovided by said piston to the space between said lower and saidintermediate sealing members and extending from such space to adjacentsaid upper sealing member, and valve means for preventing flow oflubricant through said conduit in a direction from adjacent said uppersealing member toward the space between said lower and said intermediatesealing members and for preventing flow of lubricant through saidconduit means in a direction from such space toward the sump provided bysaid piston, expansion of the space between said lower and saidintermediate sealing members drawing lubricant from the sump in saidpiston into such space through said conduit means to lubricate saidlower and said intermediate sealing members and contraction of suchspace displacing lubricant therefrom and through said conduit means tosaid upper sealing member for lubricating the latter.

References Cited in the file of this patent UNITED STATES PATENTS2,752,212 Hedges June 26, 1956

